Crankshaft construction



July 30, 1940. E. A. RYDER 2,209,542

CRANKSHAFT CONSTRUCTION Original Filed Aug. 4, 1936 "vs m '4 ATTORNEYPatented July 30, 1940 PATENT OFFICE ORANKSHAFT CONSTRUCTION Earle A.Ryder, West Hartford, Conn, assignor to United Aircraft Corporation,East Hartford,

' Conn; a corporation of Delaware Original application August 4, 1936,Serial No. 94,198. Divided and this application October 19, 1938, SerialNo. 235,806

5 Claims.

This is a division of application Serial No. 94,198 filed August 4,1936, by'Earle A. Ryder, and relates to improvements in crankshaftconstructionand has particular reference toimprovements in crankshaftsfor internal combustion engines.

An object of the invention resides in the provision of an improvedcrankshaft in which the crankpin or crankpins and the main bearingportions are made hollow andthe crankpin or crank-' pins overlap theadjacent main bearing portions by an amount somewhat greater than thewall thicknesses of these portions.

A further object resides in the provision of an improved hollowcrankshaft having cavities the intermediate portions of which are largerin cross-sectional area than the end portions.

Other objects and advantages will be more particularly pointed outhereinafter or will become apparent as the description proceedsl In theaccompanying drawing, in which like reference numerals are used to"designate similar parts throughout, there has been illustrated twoslightly different examples of what is now considered to be thepreferred manner'of carrying out the improved method forforgingirregular metal objects, such as hollow cr'anksha'fts forinternal combustion engines. The drawing, however, is for the purpose ofillustration only and is not to be taken as limiting the 'scope of whichis to be measured entirely by the scope of the appended claims.

In the drawing, Fig. 1 is an elevational view of a crankshaft at anintermediate stage of the forging process in one illustrative manner ofcarrying out the process constituting the idea of the invention.

Fig. 2 is an elevational view of'the finished crankshaft after it hasbeen formed in the manner first illustrated. g 1

Fig. 3 is an elevational view of a hollow blank used in carrying out theforging process. in a somewhat modified manner. a

Fig. 4 is an elevational view of the blank at an intermediate stage ofthe stage of. the second illustrative manner of carrying out theprocess.

Fig. 5 is an elevational view of thefinished crankshaft formed inthe'maiine'r illustrated in Figs. 3 and 4; and 7 p y Fig. 6 is anelevational view of the crankshaft taken at an angle of 90 degrees tothe view illustrated in Fig. 5. V

Referring to the drawing in detail, and particularly to Figs. 1 and 2, ametallic blank is subjected to one or more initial forging operations toprovide a partly finished article such as the crankshaft illustrated. Asshown in Fig. 1, the crankshaft has been provided with main bearingportions Ill and I2, with a crankpin portion M, with crank cheeks l6 andI8, and with counterweight extensions, broken away portions of which areindicated at and 22. In this intermediate form, the crank cheeks I6 and3 are extended so that there is no overlap of the area of the bore ofthe crankpin portion M with respect'to the main bearing portions l0 andI2. While the crankshaft is in this intermediate stage, it is renderedhollow by providing the main bearing portions I0 and I2 with straightbores 24 and 26 and the crankpin portion with a similar straight bore28. As the boring operation is performed before the overlap of thecrankpin portion of the crankshaft with respect to the main bearingportions is completed, this operation may be performed with straightboring tools in a manner commonlyemployed in machine shop practice.

' After'the bores 24, 26 and 28 are provided in the crankshaft blank,the blank is subjected'to further forging operations to provide thefinished crankshaft, as illustrated in Fig. 2. During these furtheroperations, the crank cheeks I 6 and I8 particularly are swaged downfrom their elongated condition, as illustrated in Fig. 1, to theirfinished condition, as illustrated in Fig. 2. During this 'swagingoperation, excess material which may be provided on the crank cheeks, asindicated at 30 in Fig. 1, is forced down into the main body portion ofthe finished crank cheek and at the same time the crankpin portion I4 ismoved inwardly with respect to the main bearing portions l0 and I2 untilthe bore 28 of the crankpin portion overlaps the cross-sectional areasof the main bearing portions l0 and I2. During this process,'the ends ofthe bores 24, and 28 terminating inthe crank cheeks l6 and I8 are re-'duced so that in the finished article the crankshaft cavities haveintermediate portions of approximately the same diameter asthe'respective bores provided in the blank, as illustrated in Fig. 1,but have their end portions reduced so that an adequate amount of metalis provided in the crank cheeks between thecrankpin portion and the mainbearing portions to insuresufiicient strength for the finished hollowcrankshaft.

'Vlfhileit might be possible todrill out the cavities illustrated inFig. 2 after the crankshaft was formed to its finished shape, it isobvious that the production of such irregular cavities in a metal bodywould be an extremely expensive and tedious operation requiring toolsand methods at present unknown in regular machine shop practice. Bymeans of the improved method described above, however, the desiredresult can be obtained by ordinary machine shop" methods in an operatingtime consistent with the usual practice.

If desired, the interiors of the bores formed in the blank, asillustrated in Fig. 1, may be coated with a suitable material or thehollow portions may be filled with some material before the blank issubjected to further forging operations in order to prevent scaling oroxidizing of the interior of the hollow portions during the forgingoperations, subsequent to the boring operation, required to form thefinished product.

In the slightly different manner of carrying out the improved method offorging irregular metallic bodies, as illustrated in Figs. 3, 4, 5 and6, the blank from which the body, such as an engine crankshaft, is to beformed is made hollow or tubular before the blank is subject to anyforging operation, such a hollow or tubular blank being illustrated inits initial straight condition in Fig. 3. The blank is then subjected tovarious forging operations to give it the desired form. In order to forman object such as a hollow crankshaft, the tubular blank is first formedto a generally U-shaped condition, as illustrated in Fig.4, after whichthe main bearing portions 32 and 3 5, the crankpin portion 33, and thecrank cheeks 38 and 49 are formed by subsequent operations. In carryingout the process in accordance with this second manner, the bore 42 ismaintained at substantially its original diameter through the crankpinand the main bearing portions but is materially reduced at the portionswhich extend through the crank cheeks 38 and 4t, as indicated at 44 inFigs. 5 and 6.

By employing the improved process described above, a crankshaft can beproduced in which the bore of the crankpin portion 36 overlaps thecross-sectional area of the main bearing portions 3c and 3d and in whichthe cavities in the crankpin and the main bearing portions can, in spiteof the above described overlap, be provided by usual machine shopmethods without the necessity of resorting to special tools and extendedand tedious boring or milling operations.

In the crankshaft form produced in the second described manner ofcarrying out the improved method, a crankshaft is produced which has acontinuous bore extending therethrough without any openings to theexterior of the crankshaft, such a bore having the particular advantagethat it may be used in its original form as a channel for supplyinglubricant to the various parts of the engine connected with thecrankshaft.

After the forging operations are completed,

the object, such as the crankshaft mentioned, may be subjected tovarious machining, grinding, and polishing operations to bring it to itscompletely finished form.

From the above description, it will be observed that an improved processhas been provided for forming irregular metallic objects, such ascrankshafts in which the'crankshaft comprises hollow overlapping offsetbearing portions by providing such offset portions with'bores orcavities at an intermediate stage in the formation of the object, beforeany extensive overlap of such ofiset portions is present, andsubsequently providing the offset portions with the desired amount ofoverlap after such portions have been rendered hollow, at the same timechanging the shape of the interiors of the hollow crankshaft portions aswell as the exteriors to provide the proper structure between thevarious parts when reduced to their final overlapped condition.

While there have been illustrated and described two slightly diiferentmethods by means of which the improved process may be carried out, it isto be understood that the invention is not limited to the exact methodsso illustrated and described but that such changes in the arrangement ofthe various steps of the method and in the performance of the stepsthemselves. may be resorted to as would be suggested by this disclosureto a person skilled in the art.

Having now described the invention so that others skilled in the art mayclearly understand the same, what it is desired to secure by LettersPatent is as follows:

What is claimed is.

1. As a new article of manufacture, an integral hollow forged steelcrankshaft having overlapping offset bearing portions joined byintervening crank cheeks in which the hollow interior of theintermediate bearing portion is overlapped by the end bearing portionsand the intervening crank cheek portions between the interiors of eachtwo adjoining offset bearing portions are inclined across the width ofsaid crank cheek from the end of one bearing portion to the adjacent endof the adjoining bearing portions,

2. As a new article of manufacture, an integral hollow forged crankshafthaving thin walled overlapping oifset bearing portions in which theoverlap is substantially as great as the radius of one of said bearingportions.

3. As a new article of manufacture, an integral hollow forged steelcrankshaft having overlapping offset portions in which the overlap isgreater than the wall thickness of said offset portions and each offsetsection contains a cavity having an intermediate portion ofsubstantially circular cross-section and end portions of noncircularcross-section.

4. As a new article of manufacture, an integral hollow crankshaft havingoverlapping offset bearing portions joined by intervening crank checksin which the hollow interior of the intermediate bearing portion isoverlapped by the end bearing portions and the intervening crank cheekportions between the interiors of each two adjoining offset bearingportions are inclined across the width of said crank cheek from the endof one bearing portion to the adjacent end of the adjoining bearingportion.

5. As a new article of manufacture, a crankshaft having a hollowintermediate crankpin portion and integral hollow end crank bearingportions in which the ends of the bores of the crankpin and crankbearing portions are restricted by the overlap of the crankpin with thecrank bearing vportions, said restrictions being curved on an arc ofrelatively large radius to provide thickened walls at the adjoining endsof

